Completed in 1972, the Hoheikyo Dam is the largest arch-type structure of its kind in Hokkaido. Over 40 years after its construction, weathering was found to be progressing on cliff parts at both sides of the dam. This led to concerns regarding possible rock mass failures or other hazards in the future. As the dam is a popular tourist site, investigation and design work were conducted as part of disaster prevention efforts.
In this study, the stability of rock masses was assessed as objectively as possible using advanced technology as follows:
Rock mass shapes were identified with high accuracy using high-density lasers capable of penetrating rockfall protection nets for measurement.
The severity of cracks at the back of rock masses was assessed in exploration conducted using the high-frequency impact elastic wave method.
The stability of rock masses was examined using 3D FEM analysis and limit equilibrium analysis in consideration of crack strength.
Rf:1ated influence areas were evaluated in quasi-3D rockfall simulations. and priority among different rock masses was determined for countermeasure application.
Measures implemented based on the results of this assessment included the driving of anchors from behind a large rock mass to ensure its long-term. stability without damaging the landscape.
The utilization of new technologies investigated in this study enabled the implementation of environmentally friendly countermeasures.
